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Experimental testing of inerter devices

Christakis Papageorgiou

December 2004
Technical Report: CUED/F-INFENG

Abstract

This technical report presents the results from the experimental testing of inerter devices in order to measure their admittance functions and investigate the effects of any nonlinear behaviour related to friction and backlash. The experimental testing was carried out using a Schenck hydraulic actuator which is controlled to give accurate displacement control on the movement of a hydraulic ram. The load specimen is placed between the hydraulic ram and a fixed point. The identification procedure involves the application of sinusoidal signals of various frequencies and amplitudes via the Matlab/Simulink environment interfaced with a dSPACE processor. Various internal signals are measured such as the actual ram displacement, the load force and the servo-valve current and processed appropriately to obtain the desired frequency responses. A nonlinear instability problem is identified when testing inerter devices with the Schenck hydraulic rig and a new testing methodology is proposed by employing a buffer network in series with the inerter device. An instability problem was also observed when testing pure mass loads as the mass of the load was gradually increased. The testing of inerter devices in series with a buffer removes the previously observed spiking characteristic in the measured force signal. From the estimated admittance of the inerter devices it was concluded that there exists an intermediate frequency range in which the devices behave almost as the ideal inerter. They exhibit a 20 dB/dec rise in the gain characteristic and a phase advance of almost 90 degrees. At low frequencies the devices deviate from the ideal inerter behaviour due to the presence of friction.

BibTex Entry

@TechReport{,: author = {Christakis Papageorgiou},; institution = {CUED},; title = {Experimental testing of inerter devices},; year = {2004},; month = {December},; note = {CUED/F-INFENG}
}



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